This invention relates to upright vacuum cleaners, and more particularly to dirt boxes used with such cleaners.
Upright vacuum cleaners with reusable fabric filter bags have long been provided with a dirt box at the lower or intake end of the fabric bag. Dirt-laden air from the vacuum fan flows more or less tangentially into the dirt box, and then upwardly through the dirt box and into the fabric bag. The exhaust of the dirt box may either communicate directly with the interior of the fabric bag, or it may communicate with a sleeve or "fill tube" within the fabric bag, which in turn leads to a disposable paper filter bag carried within the fabric bag. In either case, the dirt box acts as a separator to collect larger, heavier particles before they enter the dirt bag. Such particles must be cleaned out from time to time, and to this end the dirt box is provided with a removable bottom. The dirt box may also serve as a clean-out receptacle for receiving dirt from the reusable fabric bag when that bag has been relied on for primary filtering and requires cleaning out. Such a prior art upright vacuum cleaner is shown in U.S. Pat. No. 4,262,384 of common assignee.
Dirt boxes of the prior art have involved a relatively high degree of turbulence of the dirt-laden air during through-flow. This turbulence reduces air wattage and interferes with proper centrifugal action, thereby detracting from both the vacuuming and dirt-separating functions of the vacuum cleaner. Furthermore, the prior art dirt boxes have been relatively bulky and costly to manufacture.
In another aspect of upright cleaners of the prior art which use disposable bags, it has been a practice of the prior art to use helically ridged and grooved, flexible vinyl plastic tubing for the fill tube which leads from the dirt box to a fitting directly associated with the disposable paper bag, and to engage this tube over a threaded collar at the dirt box outlet and seal the two together with a surrounding tie clamp. The tie clamp involves an operation and an additional component which it is desirable to eliminate in order to reduce manufacturing costs, if such can be done without sacrificing the effectiveness and reliability of the seal.